RE: Seeking for a fifth force at the CERN Large Hadron Collider
I love these posts, short, straight to the point, and when I have finished reading them I know something new: often the mass/probability diagram are shown and it is said that when there is a bump, it is evidence of the existence of a particle, while never explaining what was actually measured (description of the axis). You managed to do that in a just few sentences: chapeau!
A question though, within the hypothesis that dark matter is made of heavy particles.
If these particles are heavy, it is because they are stable, they cannot decay into lighter ones (into particles of standard matter for example).
The reason for that would be the existence of a “parity charge”, a quantity that must be conserved, like for example the lepton number or the electric charge with standard matter.
If that is the case, how could a quark-quark collision produce a dark matter boson? In such an event, the parity would not be conserved… So within this hypothesis, quark-quark collisions would never be able to prove the existence of a "dark force"… if a new boson is discovered one day with this method, it wouldn't be related to dark matter.
Is my reasoning correct, or have I missed something?
I am not fully satisfied with my description and I still want to improve it. I liked it when I posted my article, but today, two days later... I think I can do better. Maybe in my next post on extra bosons, later this week or next week.
Dark matter can actually be light as well. The range allowed for its mass spans many many orders of magnitude (please check here for instance).
In many models, this is the case. The decay process is just forbidden by some symmetry and therefore does not happen. (By the way, the lepton number is accidentally conserved in the Standard Model; there are high energy processes where it is violated.)
The point is that a quark-antiquark collision produces a pair of dark matter particles, so that the parity is conserved. Only the production of a single dark guy is forbidden.